Good job
I did not think the reduction in drag would be worth the effort. I did not think about the increase in stability.
Did you reduce the area of the rudder, when you added the T-Foil?
A few thoughts:
The thought 10 years ago was to reduce the area by tapering the foil. I don't know what they found when they tested actual aircraft. The test data is controlled.
I have noticed that the newest aircraft have smaller winglets and there is no abrupt transition between the wing and winglet. It looks like a decreasing radi curve.
I also wonder if you need a end foil on both sides of the rudder. i.e. instead of a T could it be a L or an almost J.
I would not argue about this. It is beginning to look like the waxing or not waxing the hull debates
Carl